This invention relates generally to disposable diapers and more particularly to an improved fastening system for such diapers.
Conventional disposable diapers, in one popular construction, are comprised of a generally rectangular absorbent pad or a filler disposed between a fluid-permeable, body-facing top sheet, and a fluid-impermeable plastic film backing sheet. The filler may be comprised of typical commercially available fluff pulp while the top sheet may be comprised of a typical commerically available non-woven material and the backing sheet can be comprised of a thin sheet of polyethylene. At the side edges of the diaper the backing sheet can be folded around the edge and sealed so that a narrow strip overlies the top sheet while at the ends the backing sheet can extend loosely past the top and bottom edges providing a foldable flap to tuck in against the backing sheet upon diapering the infant.
The tapes, in a typical construction, are adhered at one end to the backing sheet while the other end can extend outwardly from the side edge or it can be folded back and adhered to a release liner fixed to the opposite side. A major problem with tapes that are fixed solely to the plastic film backing sheet is that when a person applies tension to the tape, stresses are created within the plastic film and it is likely to rupture and tear making the diaper unusable. When all of the stress is applied to the thin film, especially when attempting to pull the diaper tight about the waist of the infant, it can easily tear.
This problem has been recognized and at least two solutions have been proposed. One solution may be seen by referring to U.S. Pat. No. 3,867,940 issued FEB. 25, 1975 to Mesek et al. wherein a reinforcing scrim having a higher modulus of elasticity than the thin film backing sheet is adhered to the thin film in a location at least in the vicinity of where the tape is adhered to the thin film. This construction allows some of the stress to be taken by the stronger reinforcing material. Another solution may be seen by referring to U.S. Pat. No. 3,900,031 issued Aug. 19, 1975 to Endres et al. in which the tape tabs are attached to the backing sheet in an area where the top sheet is adhered thereto along the entire top edge. In the Endres et al. construction the filler material terminates so that it does not extend all the way in the longitudinal direction to the sealed top end margin of the diaper. Each of these tape constructions operates to solve the problem for the particular diaper construction; however, the diaper construction of the present invention is different than both Mesek et al. and Endres et al. and consequently neither tape construction is suitable to adequately reduce or prevent the tearing of the backing sheet.
Accordingly, from the foregoing an object of the present invention is to provide an improved diaper fastening system that reduces tearing of the plastic film backing sheet.
Another object of this invention is to provide a reinforced structure at the fixed end of each tape while leaving the end edge of the backing sheet free to be folded.
These and other objects of the invention will become more apparent upon reading the description to follow while referring to the drawings.